Many viruses and viroids were isolated from crops, vegetables, fruit trees, ornamental plants and herbages in Japan, and their characteristics were investigated.We provided a valuable source of relevant information that are reliable to identify. However, it is obvious that more fundamental information is required for the classification.Present status and problems in plant virus and viroid classification, and the list of viruses and viroids occurred naturally in plants in Japan have been described in the final report of research Project, grantーinーaid for scientific research.